Glider trucks, which are new trucks with old, rebuilt diesel engines mostly manufactured between 1998 and 2002, are some of the dirtiest heavy-duty trucks on the road. If left unregulated, glider trucks would create one-third of all nitrogen oxide and particulate matter emissions from heavy-duty trucks by 2025, despite comprising 5 percent of the heavy-duty fleet. EPA’s 2016 “Phase 2” medium and heavy-duty rule finalized regulations to reduce harmful glider truck emissions.

“According to internal agency research not released until after EPA published this proposal, a new 2017 glider truck can emit up to 450 times the particulate matter pollution and up to 43 times the nitrous oxide pollution of model year 2014 and 2015 trucks. Other EPA analyses concluded that, if left unregulated, glider vehicle emissions could prematurely kill thousands of people, and increase instances of lung cancer, chronic lung disease, heart disease and severe asthma attacks. We are also deeply troubled that this proposal, which appears to largely benefit a single company, was influenced by an industry-funded ‘study’ that is currently the subject of an official investigation into research misconduct for failing to adhere to basic scientific standards. We urge you to withdraw this dangerous, legally questionable proposal immediately,” the senators wrote.

Despite filing no challenge to EPA’s 2016 glider provisions in court, Fitzgerald Glider Kits and two other glider manufacturers sent a petition seeking reconsideration of the glider requirements two months after meeting with Pruitt on July 10, 2017. On Aug. 17, 2017, Pruitt sent letters to Fitzgerald and the other petitioners, saying that the petition raised “significant questions” about EPA’s legal authority “as well as the soundness of the EPA’s technical analysis” regarding glider emissions. Pruitt told the petitioners that EPA had, for legal and technical reasons, “decided to revisit” the glider rules. On Nov. 9, 2017, Pruitt signed the proposal to repeal emission standards for glider vehicles, glider engines and glider kits; and it was published on Nov. 16, 2017. Notably, on Feb. 16, 2018, the interim dean of the College of Engineering at Tennessee Tech described the only “analysis” cited by Pruitt in his decision to move forward with the rule repeal as “far-fetched” and “scientifically implausible.” The university president later asked EPA to disregard the study pending the outcome of an academic misconduct investigation into the Fitzgerald-funded “study.”

Two former EPA administrators, Carol Browner and Christine Todd Whitman, who served under Bill Clinton and George W. Bush, respectively, sent a letter to Pruitt expressing concerns over EPA’s failure to use the best science available in its decision to repeal the final glider regulations, stating, “We are deeply troubled that the Agency’s steadfast commitment to public health and environmental protection based on the best available science is being undermined.”